Incidence of cancer and mortality among employees in the asbestos cement industry in Denmark

Our plain-English summary of Incidence of cancer and mortality among employees in the asbestos cement industry in Denmark, by E. Raffn, E. Lynge, K. Juel, et al (British Journal of Industrial Medicine, 1989).

The study

• Authors: E. Raffn, E. Lynge, K. Juel, B. Korsgaard
• Journal: British Journal of Industrial Medicine
• Published: 1989;46(2):90-6
• Cited by: 91 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000144).

Abstract

In a cohort study of the incidence of cancer and mortality among 7996 men and 584 women employed in the Danish asbestos cement industry between 1928 and 1984 over 99% were traced. Chrysotile asbestos was the only fibre type used until 1946, when amosite and (in 1952) crocidolite were also introduced. Chrysotile constituted 89%, amosite 10%, and crocidolite 1% of the asbestos used. During the first 25 years of manufacture the exposure levels were high, especially in areas where the asbestos was handled dry. Measurements from 1948 indicate that the fibre levels may have ranged from 100 to 1600 times over the present Danish threshold limit value of 0.5 fibre/ml. In 1973 more than 41% of personal samples were higher than 2 f/ml. About 76% of the workforce left the factory within five years of starting employment. A total of 1346 deaths and 612 cases of cancer were observed in the cohort between 1943 and 1984. Among employed men the overall mortality (O/E 1.18; 95% CI 1.12-1.25), cancer mortality (O/E 1.32; 95% CI 1.19-1.46), and overall incidence of cancer (O/E 1.22; 95% CI 1.12-1.32) were significantly increased compared with all Danish men. This was not so among employed women. For men, significant excess risks were found for cancer of the lung (O/E 1.80; 95% CI 1.54-2.10), pleura (O/E 5.46; 95% CI 2.62-10.05), mediastinum (O/E 5.00; 95% CI 1.01-14.61), stomach (O/E 1.43; 95% CI 1.03-1.93), and other male genital organs (O/E 3.03; 95% CI 1.11-6.60). The mortality was significantly increased for men for non-malignant pulmonary diseases (O/E 1.63; 95% CI 1.33-1.98). Among the group of asbestos cement workers with first employment 1928-40 an excess risk of laryngeal cancer was found (O/E 5.50;95% CI 1.77-12.82). A total of 12 cases of pleural and one of peritoneal mesotheliomas was observed when the original notification forms were reviewed for all patients with cancer in the cohort.

In plain English

This cohort study followed 7996 men and 584 women employed 1928-84 at Danish Eternit-Fabrik Ltd in Aalborg, Denmark's only asbestos cement factory. Of the asbestos used, 89% was chrysotile, 10% amosite and 1% crocidolite. Cancers and deaths in 1943-84 were compared with expected numbers from national Danish rates. Among men, deaths were 1.18 times expected (95% CI 1.12-1.25) and cancer cases 1.22 times expected (95% CI 1.12-1.32). Among women, neither was significantly increased (deaths O/E 0.91, 95% CI 0.65-1.24; cancers O/E 1.04, 95% CI 0.71-1.47). Men had raised rates of lung cancer (162 cases; O/E 1.80, 95% CI 1.54-2.10) and of pleural tumours (10 registry cases, all mesotheliomas; O/E 5.46, 95% CI 2.62-10.05). They also had raised rates of mediastinal, stomach and penile cancer, and excess deaths from non-malignant lung disease. Reviewing notification forms brought the total to 12 pleural and one peritoneal mesothelioma, all in men. Laryngeal cancer was significantly raised only among asbestos cement workers first employed 1928-40. Since amosite and crocidolite exposure could not be excluded, the authors stated the study cannot show whether chrysotile alone causes mesothelioma. The workers' smoking habits were never studied.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Historical cohort study of cancer incidence and mortality, comparing observed numbers with expected numbers from national Danish rates (O/E ratios with 95% confidence intervals)
• Who was studied: Everyone ever employed from 1928 to 1984 at Danish Eternit-Fabrik Ltd, Aalborg, Denmark: 7996 men and 584 women, over 99% traced. Cancers and deaths were counted from 1943 to 1984.
• Exposure: Work in asbestos cement manufacture (building materials and pipes). Only chrysotile was used until 1946; amosite was introduced in 1946 and crocidolite in 1952. Overall, chrysotile made up 89% of the asbestos used, amosite 10% and crocidolite 1%. Fibre levels were estimated at 50 to 800 f/ml in 1948 and 10 to 100 f/ml in 1957. In 1973, 41% of personal samples were above 2 f/ml (the abstract says more than 41%). About 76% of the workforce left within five years.
• Main results:
  • Men: overall mortality was significantly increased (O/E 1.18; 95% CI 1.12-1.25). Malignant tumours caused 359 deaths against 272.44 expected.
  • Men: 580 cancer cases were observed against 477.46 expected (O/E 1.22; 95% CI 1.12-1.32).
  • Women: overall mortality was not increased (observed 40, expected 43.90, O/E 0.91; 95% CI 0.65-1.24).
  • Women: overall cancer incidence was not increased (observed 32, expected 30.7; O/E 1.04; 95% CI 0.71-1.47).
  • Men: 162 lung cancer cases were observed against 89.81 expected (O/E 1.80; 95% CI 1.54-2.10).
  • Men: the lung cancer relative risk rose with time since first employment up to the 30-34 year interval (O/E 2.77), then decreased.
  • Using duration of employment as a stand-in for dose, no dose-response relation was found for lung cancer.
  • Men: 10 malignant tumours of the pleura were observed in the registry data against 1.83 expected (O/E 5.46; 95% CI 2.62-10.05). All were mesotheliomas.
  • Review of the original notification forms identified three more mesotheliomas, giving 12 pleural and one peritoneal mesothelioma, all in men. Five were among asbestos cement workers first employed before 1941, and none among cement workers employed at that time.
  • Men: excess risk of malignant tumours of the mediastinum (3 observed, 0.60 expected; O/E 5.00; 95% CI 1.01-14.61).
  • Men: among digestive cancers, only stomach cancer was significantly raised (O/E 1.43; 95% CI 1.03-1.93).
  • Men: laryngeal cancer was not significantly raised among all men (O/E 1.66; 95% CI 0.91-2.78).
  • Laryngeal cancer was significantly raised among asbestos cement workers first employed 1928-40 (n = 269): 5 observed against 0.91 expected (O/E 5.50; 95% CI 1.77-12.82).
  • Men: other male genital cancers were significantly raised (O/E 3.03; 95% CI 1.11-6.60). All cases were penile cancers.
  • Men: non-malignant pulmonary diseases caused 102 deaths against 62.65 expected (O/E 1.63; 95% CI 1.33-1.98).
• The authors' conclusion: The authors stated that, although the factory mainly used chrysotile, exposure to amosite and crocidolite could not be excluded for the mesothelioma cases. The study therefore does not show whether chrysotile alone in asbestos cement manufacture may cause mesothelioma.
• Limitations the authors state:
  • Smoking habits among the employees were never studied. A 1973 survey found that cement workers in Aalborg smoked 3-4% more than other men in the city, a difference the authors judged unlikely to explain the excess of lung cancer.
  • For workers first employed 1928-42, cement workers may occasionally have worked in the asbestos cement area.
  • Short-term employees may also have been exposed to other carcinogens during their working careers.
  • Unskilled workers, who are somewhat over-represented in the cohort, have an increased risk of stomach cancer in Denmark.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Cohort Study, Chrysotile, Amosite, Crocidolite, Threshold Limit Value (TLV), Personal Breathing Zone Sample, Pleura.

Related studies

• Incidence of lung cancer by histological type among asbestos cement workers in Denmark — E. Raffn, E. Lynge, et al. (1993)
• A cohort study on mortality among wives of workers in the asbestos cement industry in Casale Monferrato, Italy — C. Magnani, B. Terracini, et al. (1993)
• Lung cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Update of mortality and cancer incidence in the Australian petroleum industry cohort — R.T. Gun, N. Pratt, et al. (2006)
• Incidence, mortality and survival in malignant pleural mesothelioma before and after asbestos in Denmark, Finland, Norway and Sweden — K. Hemminki, A. Försti, et al. (2021)

Browse more research in British Journal of Industrial Medicine, or return to medical research.